/*
 *
 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    Licensed under the Apache License, Version 2.0 (the "License");
 *  *    you may not use this file except in compliance with the License.
 *  *    You may obtain a copy of the License at
 *  *
 *  *        http://www.apache.org/licenses/LICENSE-2.0
 *  *
 *  *    Unless required by applicable law or agreed to in writing, software
 *  *    distributed under the License is distributed on an "AS IS" BASIS,
 *  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  *    See the License for the specific language governing permissions and
 *  *    limitations under the License.
 *
 */

package org.deeplearning4j.base;

import lombok.Data;
import lombok.NoArgsConstructor;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.codec.digest.DigestUtils;

import org.deeplearning4j.util.ArchiveUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
@Data
@NoArgsConstructor
public class MnistFetcher {
	protected static final Logger log = LoggerFactory.getLogger(MnistFetcher.class);

	protected File BASE_DIR = new File(System.getProperty("user.home"));
	protected static final String LOCAL_DIR_NAME = "MNIST";
	protected File FILE_DIR = new File(BASE_DIR, LOCAL_DIR_NAME);

	private File fileDir;
	private static final String trainingFilesURL = "http://yann.lecun.com/exdb/mnist/train-images-idx3-ubyte.gz";
	private static final String trainingFilesMD5 = "f68b3c2dcbeaaa9fbdd348bbdeb94873";
	private static final String trainingFilesFilename = "images-idx3-ubyte.gz";
	public static final String trainingFilesFilename_unzipped = "images-idx3-ubyte";
	private static final String trainingFileLabelsURL = "http://yann.lecun.com/exdb/mnist/train-labels-idx1-ubyte.gz";
	private static final String trainingFileLabelsMD5 = "d53e105ee54ea40749a09fcbcd1e9432";
	private static final String trainingFileLabelsFilename = "labels-idx1-ubyte.gz";
	public static final String trainingFileLabelsFilename_unzipped = "labels-idx1-ubyte";

	//Test data:
	private static final String testFilesURL = "http://yann.lecun.com/exdb/mnist/t10k-images-idx3-ubyte.gz";
	private static final String testFilesMD5 = "9fb629c4189551a2d022fa330f9573f3";
	private static final String testFilesFilename = "t10k-images-idx3-ubyte.gz";
	public static final String testFilesFilename_unzipped = "t10k-images-idx3-ubyte";
	private static final String testFileLabelsURL = "http://yann.lecun.com/exdb/mnist/t10k-labels-idx1-ubyte.gz";
	private static final String testFileLabelsMD5 = "ec29112dd5afa0611ce80d1b7f02629c";
	private static final String testFileLabelsFilename = "t10k-labels-idx1-ubyte.gz";
	public static final String testFileLabelsFilename_unzipped = "t10k-labels-idx1-ubyte";


	public  File downloadAndUntar() throws IOException {
		if (fileDir != null) {
			return fileDir;
		}

		File baseDir = FILE_DIR;
		if (!(baseDir.isDirectory() || baseDir.mkdir())) {
			throw new IOException("Could not mkdir " + baseDir);
		}

		log.info("Downloading mnist...");
		// getFromOrigin training records
		File tarFile = new File(baseDir, trainingFilesFilename);
		File testFileLabels = new File(baseDir, testFilesFilename);

		tryDownloadingAFewTimes(new URL(trainingFilesURL), tarFile, trainingFilesMD5);

		tryDownloadingAFewTimes(new URL(testFilesURL), testFileLabels, testFilesMD5);

		ArchiveUtils.unzipFileTo(tarFile.getAbsolutePath(), baseDir.getAbsolutePath());
		ArchiveUtils.unzipFileTo(testFileLabels.getAbsolutePath(), baseDir.getAbsolutePath());

		// getFromOrigin training records
		File labels = new File(baseDir, trainingFileLabelsFilename);
		File labelsTest = new File(baseDir, testFileLabelsFilename);

		tryDownloadingAFewTimes(new URL(trainingFileLabelsURL), labels, trainingFileLabelsMD5);
		tryDownloadingAFewTimes(new URL(testFileLabelsURL), labelsTest, testFileLabelsMD5);

		ArchiveUtils.unzipFileTo(labels.getAbsolutePath(), baseDir.getAbsolutePath());
		ArchiveUtils.unzipFileTo(labelsTest.getAbsolutePath(), baseDir.getAbsolutePath());

		fileDir = baseDir;
		return fileDir;
	}

	private void tryDownloadingAFewTimes(URL url, File f, String targetMD5) throws IOException {
		tryDownloadingAFewTimes(0, url, f, targetMD5);
	}

	private void tryDownloadingAFewTimes(int attempt, URL url, File f, String targetMD5) throws IOException {
		int maxTries = 3;
		boolean isCorrectFile = f.isFile() && checkMD5OfFile(targetMD5, f);
		if (attempt < maxTries && !isCorrectFile) {
			FileUtils.copyURLToFile(url, f);
		} else {
			throw new IOException("Could not download " + url.getPath() + "\n properly despite trying " + maxTries + " times, check your connection.");
		}
		if (!isCorrectFile) tryDownloadingAFewTimes(attempt + 1, url, f, targetMD5);
	}

	private boolean checkMD5OfFile(String targetMD5, File file) throws IOException {
		InputStream in = FileUtils.openInputStream(file);
		String trueMd5 = DigestUtils.md5Hex(in);
		IOUtils.closeQuietly(in);
		return (targetMD5.equals(trueMd5));
	}

	public static void gunzipFile(File baseDir, File gzFile) throws IOException {
		log.info("gunzip'ing File: " + gzFile.toString());
		Process p = Runtime.getRuntime().exec(String.format("gunzip %s",
				gzFile.getAbsolutePath()));
		BufferedReader stdError = new BufferedReader(new
				InputStreamReader(p.getErrorStream()));
		log.info("Here is the standard error of the command (if any):\n");
		String s;
		while ((s = stdError.readLine()) != null) {
			log.info(s);
		}
		stdError.close();
	}


}
